Poultom , or bird-optical dinosaurs, or ornithiskhia (Lat. Ornithischia), is one of the two main treasure of dinosaurs, considered in the rank of the detachment. Despite its name, not they, and the lizardous dinosaurs in the most common version gave the beginning of the birds, which now usually also include the composition of the lizardos.
Were roasting (with the exception of early omnivorous species), smaller than the lizard-duty barriers. In addition to the most primitive, there are fittings for plant food: complex intestines and cheeks. Early representatives were two-legged, later bird retailetasis re-mastered walking in four limbs. During the evolution of the late representatives of the detachment, the end phalanges of the fingers became more flat and acquired the species of hoofs. Many have developed adaptations to protect against predators: armor, horns, spikes.
The pelvis had a four-world structure. The pubic bone had a rise, directed backwards along the sedlication bone (in the lizardous bones were practically perpendicular to). Lobcovaya bone often forms a new increase, directed forward parallel to the spine. A similar structure of the pelvis developed in dinosaurs independently three times: in the bird spectatase, the Superizinosauridea family and the Dromaeosauridae family. The last and is the most likely ancestor of birds.
Some species (Hypsilophodon, Talenkauen and TheScelosaurus) have interrog locative bone plates in the front of the Röbebe. Some researchers suggest that these plates performed biomechanical functions, helped in breathing or to ensure increased rigidity of the front of the chest, while others believe they served for defensive functions.
The analysis of the remains of the dinosaurs existing scientists allowed them to determine that the lizards of this detachment first appeared in Late Triassa, about 220 million years ago and were extremely small. This dinosaur detachment began to violently evolve only in the subsequent Jurassic period (208-144 million years ago), more and more spreading on the planet and occupying environmental niches after the disappearance of other herbivores.
The earliest of famous bird-made dinosaurs is the Pisanosaurus (Pisanosaurus), found in the rocks of the Upper Triass on the territory of modern Argentina. The family of forest marks from the Jurassic sediments of South Africa is best studied. Like all other early bird spectacular dinosaurs, it reached a length of about 1 meter. The structure of the hind limbs is characteristic of bipedal animals, the large ber bone is much longer than the femoral. Some parts of the skeleton are similar to those of the early teropod, but the pelvic bones and the structure of the skull and teeth already have signs of bird spectacular dinosaurs
Previously, the poultomists were divided into 4 or 6 subversions, including thyreophores (otherwise), horned dinosaurs (ceratops), ankylosaurs (shell dinosaurs), ceraperics (the most famous representatives of whom are iguanodones) and piccirogol Pakhiceofalosaurov. Currently, they are divided into two sub-train-treasures: thyroid phosphors and ceraperics. The first includes the infralls of the stentor and ankylosaurs, the second-horned dinosaurs and Pakhiceophalosaurov (for their part, often united in the cland or the marginocephalov arrivals), as well as ornithopods (including iguanodones, waterproof gardensavrov, etc.)
